I'm not deriving theories, perhaps I'm talking truth. It is you who are deriving theories by writing senseless comments like "Up rjy all trains runs fine...later this worst region where railways don't maintain properly. May its two zones border." without even some common sense. No matter what, until the last centimeter of the border, zone has to maintain the tracks. Just because its the end of the zone, they wouldn't neglect, especially in BZA-VSKP stretch.
Most of the times, Temporary Speed Restrictions means that the particular area is undergoing some sort of maintenance, however there are exceptions though.